Copy text in TextBox in another Interface

HI

I have a text box say tx1, in Interface 1  

and another text box say tx2, in interface 2.

Interface 2 will be changed from time to time

I want textbox in interface 1  always to show the text that appears in interface 2.

In  tx1 settings in interface 1 I need to show something like --

=interface 2,tx2\n                 ....  9tx2 being the id of text box to copy

This is not working, need some advice.

Both tx1 and tx2  set at    --   local setting

Is there a better way to do this with text log or  similar

Thankyou
Charles Harris